Linux Fundamentals Note

Lecture 1: Setting Up a Linux Practice Environment

In this lecture, I learned how to set up a basic Linux practice environment using Oracle VM VirtualBox and Ubuntu Linux. Instead of installing Linux directly on my main computer, I used a virtual machine so I could practice safely inside my existing Windows environment.

The overall setup process was:

-> Download VirtualBox
-> Download the Ubuntu ISO file
-> Install VirtualBox
-> Create a new virtual machine
-> Allocate RAM and virtual disk space
-> Boot and install Ubuntu

Downloading VirtualBox

VirtualBox is a virtualization tool that allows one computer to run another operating system inside a virtual machine. In this setup, Windows acts as the host operating system, and Ubuntu runs as the guest operating system.

Downloading Oracle VM VirtualBox from the official website

Key Takeaways

• VirtualBox allows me to create and run virtual machines.
• A virtual machine uses part of the real computer’s CPU, memory, disk, and network resources.
• This is a safe way to practice Linux without changing the main operating system.

Downloading Ubuntu

Ubuntu is a popular Linux distribution that is commonly used for learning, desktop use, servers, and cloud environments. For this lecture, I downloaded the Ubuntu Desktop ISO file and used it as the installer inside VirtualBox.

Selecting the Ubuntu Desktop download option

What Is an ISO File?

An ISO file is a disk image used to install an operating system. In a physical setup, an operating system might be installed from a DVD or USB drive. In VirtualBox, the ISO file can be attached like a virtual installation disk.

Installing VirtualBox

After downloading the installer, I launched the VirtualBox setup wizard and continued with the default installation options. The installer includes components such as the main VirtualBox application, USB support, and networking support.

Installing VirtualBox with the default setup components

Why These Components Matter

• VirtualBox Networking allows the guest operating system to connect to networks.
• VirtualBox USB Support allows USB devices to be used inside virtual machines.
• The default installation options are usually enough for a beginner Linux lab.

Creating a Virtual Machine and Allocating Resources

After installing VirtualBox, I created a new virtual machine for Ubuntu. I selected Linux as the operating system type and Ubuntu as the version. Then I configured the amount of memory and storage assigned to the virtual machine.

One important part of this lecture was understanding how to allocate RAM.

RAM Allocation

RAM is the memory used while the virtual machine is running. When I assign RAM to Ubuntu in VirtualBox, that memory comes from the physical computer.

• If I assign too little RAM, Ubuntu may run slowly.
• If I assign too much RAM, the host operating system may become slow.
• For a basic Ubuntu lab, 2 GB or more is usually enough for simple practice.
• The best setting depends on how much total RAM the physical computer has.

Host OS: the main operating system running on the physical computer
Guest OS: the operating system running inside the virtual machine

Creating a Virtual Hard Disk

A virtual machine does not use a physical hard drive directly. Instead, it stores its operating system and files inside a virtual disk file. In this lecture, I created a virtual disk named Linux.vdi and assigned it 10 GB of storage.

Creating a virtual hard disk for the Ubuntu virtual machine

VDI

VDI stands for Virtual Disk Image. It is the virtual hard disk format used by VirtualBox. To the Ubuntu guest operating system, the VDI file appears like a normal hard drive.

Booting Ubuntu

After creating the virtual machine and attaching the Ubuntu ISO file, I started the machine. The Ubuntu boot screen appeared inside the VirtualBox window.

Ubuntu booting inside Oracle VM VirtualBox

The bottom-right corner shows Right Control, which is the VirtualBox Host Key. It can be used to release keyboard or mouse control from the virtual machine back to the host computer.

Ubuntu Installation Screen

The Ubuntu installer provides two main choices: Try Ubuntu and Install Ubuntu.

Ubuntu installation welcome screen

Try Ubuntu vs. Install Ubuntu

• Try Ubuntu: runs Ubuntu temporarily without installing it.
• Install Ubuntu: installs Ubuntu onto the virtual hard disk.

For this lab, I selected Install Ubuntu so I could create a reusable Linux practice environment.

Ubuntu Login Screen

After the installation completed, the virtual machine rebooted into Ubuntu and displayed the login screen. From here, I could select the user account and sign in to the Ubuntu desktop.

Ubuntu login screen after installation

The message at the top indicates that the guest operating system supports mouse integration. This makes it easier to move the mouse between the host operating system and the virtual machine.

Core Concepts Learned

VirtualBox

VirtualBox is a virtualization platform that allows me to run another operating system inside my current computer.

Ubuntu

Ubuntu is a Linux distribution. It provides a desktop environment and is widely used for learning Linux fundamentals.

Virtual Machine

A virtual machine is a software-based computer that uses allocated resources from the physical computer, including RAM, CPU, storage, and networking.

RAM Allocation

RAM allocation determines how much memory the guest operating system can use. It is important to provide enough memory for Ubuntu while still leaving enough resources for the host operating system. I set it as 1024MB. (Enough for learning/experiment purpose)

Virtual Hard Disk

A virtual hard disk stores the guest operating system and files. In VirtualBox, this can be saved as a .vdi file.

ISO

An ISO file is an installation disk image. In this lab, the Ubuntu ISO was attached to the virtual machine to start the installation process.

Lecture 2: Basic Terminal Commands and Command History

Printing Text with echo

echo "Hello, Linux"

Hello, Linux

Checking Time Settings with timedatectl

The timedatectl command displays the system clock and time configuration managed by systemd.

timedatectl

Its output can include:

• Local time: the current time in the configured time zone.
• Universal time: the current Coordinated Universal Time (UTC).
• RTC time: the hardware real-time clock value.
• Time zone: the system’s configured geographic time zone.
• System clock synchronized: whether the system clock is synchronized.
• NTP service: whether network-based time synchronization is active.

This command is useful when checking a Linux machine’s time zone or diagnosing incorrect system time.

Clearing the Terminal with clear

clear

Viewing Previous Commands with history

history

Example:

1  echo "Hello, Linux"
2  timedatectl
3  clear
4  history

Command history is useful for reviewing previous work, finding a long command, and avoiding unnecessary retyping.

Recalling Commands with the Up Arrow Key

Pressing the Up Arrow key recalls an earlier command at the prompt. Pressing it repeatedly moves backward through the command history.

Press Up Arrow -> review the command -> edit if needed -> press Enter

This method is useful when I want to inspect or modify a previous command before running it again.

Repeating the Last Command with !!

The !! history expansion runs the immediately preceding command again.

echo "Hello, Linux"

Hello, Linux

!!

Hello, Linux